1. Field of the Invention
The present invention relates to well completion; more particularly the present invention relates to methods and apparatus involving the use of expandable tubulars in a wellbore; still more particularly the invention includes trip saving methods and apparatus for use with expandable sand screen.
2. Background of the Related Art
The completion of wells includes the formation of a borehole to access areas of the earth adjacent underground formations. Thereafter, the borehole may be lined with steel pipe to form a wellbore and to facilitate the isolation of a portion of the wellbore with packers. The casing is perforated adjacent the area of the formation to be accessed to permit production fluids to enter the wellbore for recovery at the surface of the well. Whether the well is drilled to produce hydrocarbons, water, geothermal energy, or is intended as a conduit to stimulate other wells, the basic construction is the same. In addition to creating and perforating a wellbore, the formation surrounding a wellbore may be treated to enhance production of the well. For example, when a formation having very low permeability, but a sufficient quantity of valuable fluids is to be produced, it is necessary to artificially increase the formation""s permeability. This is typically accomplished by xe2x80x9cfracturingxe2x80x9d the formation, a practice which is well known in the art and for which purpose many methods have been conceived. Basically, fracturing is achieved by applying sufficient pressure to the formation to cause it to crack or fracture, hence the term xe2x80x9cfracturingxe2x80x9d or simply xe2x80x9cfracingxe2x80x9d. The desired result of this process is that the cracks interconnect the formation""s pores and allow the valuable fluids to be brought out of the formation and to the surface.
The general sequence of steps needed to stimulate a production zone through which a wellbore extends is as follows: First, a performable nipple is made up in the well casing and cemented in at a predetermined depth in the well within the subterranean production zone requiring stimulation. Next a perforating trip is made by lowering a perforation assembly into the nipple on a tubular work-string. The perforating assembly is then detonated to create a spaced series of perforations extending outwardly through the nipple, the cement and into the production zone. The discharged gun assembly is then pulled up with the workstring to complete the perforating trip. Thereafter, stimulating and fracturing materials are injected into the well.
Another frequently used technique to complete a well is the placement of sized gravel in an annular area formed between the perforated casing and a screen member disposed on the end of tubing that is coaxially inserted into the wellbore as a conduit for production fluids. In order to eliminate or reduce the production of formation sand, a sand screen is typically placed adjacent to the perforations or adjacent to an open wellbore face through which fluids are produced. A packer is usually set above the sand screen and the annulus around the screen is then packed with a relatively course sand, commonly referred to as gravel, to form a gravel pack around the sand screen as well as in the perforations and/or in the producing formation adjacent the well bore for filtering sand out of the in-flowing formation fluids. In open hole gravel pack installations, the gravel pack also supports the surrounding unconsolidated formation and helps to prevent the migration of sand with produced formation fluids.
Recently, technology has arisen making it possible to expand a tubular in a wellbore. These in-situ expansion apparatus and methods permit a tubular of a smaller diameter to be inserted into a wellbore and then expanded to a larger diameter once in place. The advantages of time and space are obvious. The technique has also be applied to sand screens, or those tubulars members at the lower end of production tubing designed to permit the passage of production fluid therethrough but to inhibit the passage of particulate matter, like sand. An expandable slotted tubular usable as a sand screen and a method for its use is described in published Application No. PCT/GB98/03261 assigned to the same entity as the present application, and that publication is incorporated herein by reference in its entirety.
An expandable sand screen is typically inserted into a wellbore on the end of a run-in string of tubulars with its initial outer diameter about the same as the diameter of the run-in string. In one method of in-situ expansion, a wedge-shaped cone member is also run into the well at an upper or lower end of the expandable screen with the tapered surface of the cone decreasing in diameter in the direction of the expandable screen. The cone typically is mounted on a separate string to permit it to move axially in the wellbore independent of the expandable screen. At a predetermined time, when the screen is fixed in the wellbore adjacent that portion where production fluid will enter the perforated casing, the cone is urged through the expandable screen increasing its inner and outer diameters to the greatest diameter of the cone. Due to physical forces and properties, the resulting expanding screen is actually larger in inside diameter thus the outside diameter of the core.
In one technique, the cone is pulled up through the screen and then removed from the well with the run-in string. In another technique, the cone is used in a top-down fashion and is either dropped to the bottom of the well or is left at the bottom end of the well screen where it does not interfere with fluid production through the expanded well screen thereabove. In another method of expansion, an expansion tool is run into the wellbore on a string of tubulars to a location within the tubular to be expanded. The expansion tool includes radially expandable roller members which can be actuated against the wall of a tubular via fluid pressure. In this manner, the wall of the tubular can be expanded past its elastic limits and the inner and outer diameter of the tubular is increased. The expansion of the tubular in the case of expandable well screen is facilitated by slots formed in the wall thereof.
An expander tool usable to expand solid or slotted tubulars is illustrated in FIGS. 1-3. The expansion tool 100 has a body 102 which is hollow and generally tubular with connectors 104 and 106 for connection to other components (not shown) of a downhole assembly. FIGS. 1 and 2 are perspective side views of the expansion tool and FIG. 3 is an exploded view thereof. The end connectors 104 and 106 are of a reduced diameter (compared to the outside diameter of the longitudinally central body part 108 of the tool 100), and together with three longitudinal flutes 110 on the central body part 108, allow the passage of fluids between the outside of the tool 100 and the interior of a tubular therearound (not shown). The central body part 108 has three lands 112 defined between the three flutes 110, each land 112 being formed with a respective recess 114 to hold a respective expandable member 116. Each of the recesses 114 has parallel sides and extends radially from the radially perforated tubular core 115 of the tool 100 to the exterior of the respective land 112. Each of the mutually identical rollers 116 is near-cylindrical and slightly barreled. Each of the rollers 116 is mounted by means of a bearing 118 at each end of the respective roller for rotation about a respective rotation axis which is parallel to the longitudinal axis of the tool 100 and radially offset therefrom at 120-degree mutual circumferential separations around the central body 108. The bearings 418 are formed as integral end members of radially slidable pistons 120, one piston 120 being slidably sealed within each radially extended recess 114. The inner end of each piston 120 (FIG. 2) is exposed to the pressure of fluid within the hollow core of the tool 100 by way of the radial perforations in the tubular core 115.
While expandable sand screen is useful in wells to eliminate the annular area formed between a conventional screen and a casing, its use can add yet another step to the completion of a well and requires at least an additional trip into the well with a run-in string of tubular in order to expand the screen. Because the various completion operations described are performed in separate and time consuming steps, there is a need for well completion apparatus and methods using expandable well screen that combines various completion steps and decreases time and expense associated with completing a well.
In one aspect of the invention apparatus and methods are provided for completing a wellbore using expandable sand screen. An apparatus including a section of expandable sand screen, and an expanding member is disposed in the wellbore on a tubular run-in string. Thereafter, the expandable sand screen is expanded in a producing area of the wellbore. In another aspect of the invention, the apparatus includes a packer above and below the section of expandable sand screen to isolate the wellbore above and below the sand screen. In another aspect of the invention, the apparatus includes a perforating assembly which is utilized to form perforations in a wellbore casing and thereafter, the expandable sand screen is expanded in the area of the perforations. In another aspect of the invention, wellbore casing is perforated and subsequently treated with fracturing materials before a section of sand screen is expanded in the area of the perforations. In another aspect of the invention, an annular area between the unexpanded sand screen and perforated casing is filled with a slurry of gravel. Thereafter, the expandable sand screen is expanded in the area of the perforations and the gravel is compressed between the sand screen and the perforated casing wall. In another aspect of the invention, a method is disclosed including the steps of running an apparatus into a wellbore, anchoring a section of well screen in the wellbore, perforating the wellbore, disposing the sand screen in the wellbore in the area of the perforations and expanding the sand screen in the area of the perforations.